Solid-state image pickup device for auto-focus and auto-focus camera using the same

ABSTRACT

The invention provides a solid-state image pickup device for an auto-focus and a camera for an auto-focus in which focusing precision is improved. The device has first and second linear sensor pairs (for example,  2 - 1, 2 - 2 ) each having a linear sensor for a base portion with a plurality of pixels and a linear sensor for a reference portion with a plurality of pixels in order to perform a focal point detection of a TTL passive-type phase detection system. The first and second linear sensor pairs have the same pixel pitch, the first and second linear sensor pairs arm neighboring in parallel and are arranged so as to be relatively deviated in the arranging direction of the linear sensors, and a signal output to detect the focal point is executed by using both of the first and second linear sensor pairs.

TECHNICAL FIELD

The invention relates to realization of high precision of a solid-stateimage pickup device for auto-focus (hereinbelow, also referred to as AF)and, more particularly, to an AF sensor of a TTL-SIR (Through The LensSecondary Imaged Registration: secondary image forming phase differencedetection) type and an AF camera using such an AF sensor.

BACKGROUND ART

A conventional TTL-SIR type AF sensor has been disclosed in detail in“CMOS Linear Auto-focus Sensor for 7-point Wide Area Auto-focus System”,ITE Technical Report, Vol. 25, No. 28, pp. 1-6, 2001, or the like by theapplicant of the present invention.

FIG. 9 shows a layout of linear sensors of such a solid-state imagepickup device for AF. To perform the detection of 7 points including thecenter cross detection, eight linear sensor pairs 131 are arranged on asame semiconductor substrate 130 in correspondence to the detectingpoints. By arranging two kinds of linear sensor pairs in the horizontaland vertical directions in a crucial shape with respect to the centerdetecting point, the cross AF for executing both of the vertical linedetection and the lateral line detection can be realized. In thosedevices, a light beam which passed through a photographic lens is guidedto a linear sensor 132 for a base portion and a linear sensor 133 for areference portion arranged on the AF sensor. Two object images areformed again at two positions on the linear sensors 132 and 133 by asecondary image forming optical system and a phase difference betweenthose two object images is detected, thereby obtaining a defocusingamount (actually, by executing a correlation arithmetic operation of asignal of the base portion and a signal of the reference portion,resolution of focusing precision is improved). Detecting precision inthe above system largely depends on a pixel pitch and a base-line lengthof the linear sensor (distance between an optical center of the linearsensor for the base portion and that of the linear sensor for thereference portion). Generally, if the pixel pitch is small and thebase-line length is large, the focusing precision can be raised more.However, if the base-line length is increased, a chip size and a size ofoptical unit also increase. Therefore, if the pixel pitch is decreases,it is more effective for miniaturization of the camera.

Several techniques of improving the focusing precision by another methodhave been also disclosed. A focus detecting apparatus of a camera whichhas a sensor array of a large pixel pitch and a sensor array of a smallpixel pitch and in which, when a focus detection is disabled in onesensor array, the focus detection is executed by using an output of theother sensor array is disclosed in Japanese Patent Application Laid-OpenNo. S64-80920. An apparatus in which, as a sampling pitch for samplingan object image, a plurality of kinds of sampling pitches including aninitial state can be selected and, by switching the pixel pitch inaccordance with a spatial frequency of an object and executing the focusdetection, the focusing precision can be improved has also beendisclosed in Japanese Patent Application Laid-Open No. H11-14900. Thefocusing precision can be improved by providing one more linear sensorother than the linear sensors which are ordinarily used or by changingthe pixel pitch. A capturing ratio (ratio at which the object can befocused) of the object is also improved.

In the above conventional techniques, however, since there issensitivity distribution also in the pixel, there is a case where theprecision deteriorates in dependence on the image forming position ofthe object image. The case where the focusing precision deteriorateswill be described hereinbelow.

FIG. 10 is a diagram showing sensitivity distribution within a cellalong the horizontal direction in the pixel of the general AF sensor.The sensitivity at the center of each of photodiodes 110-1 to 110-5serving as pixels is the highest. As the position approaches the pixeledge, the sensitivity deteriorates and the sensitivity in an isolationregion 128 is low. FIG. 11 shows a relation between an object imageformed on the photodiode 110-3 and outputs from the AF sensor regardingthe photodiodes 110-1 to 110-5. In FIG. 11, the object image is formedat almost the center of the photodiode 110-3, so that the output of thephotodiode 110-3 is the largest. The signals of the photodiodes 110-2and 110-4 adjacent to the photodiode 110-3 are outputted at a certainratio due to crosstalks from the photodiode 110-3. If the object imageis formed in the isolation region between the photodiodes 110-3 and110-4 as shown in FIG. 12, since magnitudes of the outputs of thephotodiodes 110-3 and 110-4 are almost equal, it is determined to beunspecified that in which pixel on the right or left side of theisolation region a peak of the object image is located. Thus, even ifthe same object is auto-focused, an arithmetic operation result differsevery time. To reduce such an influence, it is preferable to reduce thehorizontal pixel pitch. For example, if the pixel pitch is reduced tothe half, a focusing error is also reduced to about the half. However,since the sensitivity deteriorates if the pixel pitch is simply reduced,there is a case where the AF itself cannot be performed at the time oflow luminance. To reduce the pixel pitch without deteriorating thesensitivity, it is required to introduce a fine-patterning process.However, since a long developing period of time and very high developingcosts are necessary to accomplish the fine-patterning process, it isdifficult to develop the solid-state image pickup device for the AF withlow costs in a short period of time.

DISCLOSURE OF THE INVENTION

It is an object of the invention to realize a solid-state image pickupdevice for the AF having AF performance of high precision.

Another object of the invention is to realize a solid-state image pickupdevice for the AF having AF performance of a high sensitivity.

Still another object of the invention is to realize a solid-state imagepickup device for an AF which can accomplish the above objects withoutneeding the fine-patterning process.

To accomplish the above objects, according to the invention, there isprovided a solid-state image pickup device for an auto-focus comprisingfirst and second linear sensor pairs each having a linear sensor for abase portion with a plurality of pixels and a linear sensor for areference portion with a plurality of pixels in order to perform a focalpoint detection of a TTL passive-type phase detection system, whereinthe first linear sensor pair and the second linear sensor pair have thesame pixel pitch, the first linear sensor pair and the second linearsensor pair are neighboring in parallel and are arranged so as to berelatively deviated in the arranging direction of the linear sensor forthe base portion and the linear sensor for the reference portion (zigzaglayout), and a signal output to detect the focal point is executed byusing both of the first linear sensor pair and the second linear sensorpair. In the construction of the invention, in the case where the objectimage is formed in the isolation region of one linear sensor pair andthe detection result becomes unstable, the focal point can be detectedby the other linear sensor pair in which the pixels have been deviated,so that the deterioration of the focusing precision can be eliminated.By equivalently reducing the pixel pitch to the half, the focusingprecision can be also improved.

In the invention, by line-symmetrically arranging the two linear sensorpairs, the two linear sensor pairs are closely arranged, so that adetection error for the positional deviation of the object iseliminated.

In the invention, by arranging two sets of linear sensors havingdifferent base-line lengths on the same straight line., the higherprecision AF can be realized.

In the invention, by using the linear sensor pair arranged in a zigzagshape and the two kinds of linear sensor pairs having differentbase-line lengths arranged in the direction which perpendicularlycrosses zigzag-shaped linear sensor pair, the crossing point can bedetected and both of the high-precision AF and the high-sensitivity AFcan be realized.

According to the invention, the solid-state image pickup device for theAF having the high precision, high stability, high object capturingratio, and high sensitivity can be realized. By forming an intelligentcircuit board on which the various functions of the invention have beenbuilt as one chip, both of the miniaturization and low costs of thedevice are also realized. Therefore, the solid-state image pickup devicefor the AF which is optimum for use in a small digital single-lensreflex camera of a low price can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a layout of the first embodiment of theinvention;

FIG. 2 is a constructional diagram of an AF circuit of the firstembodiment of the invention;

FIG. 3 is a diagram showing constructions of a maximum value detectioncircuit and a minimum value detection circuit in the AF circuitconstruction mentioned above;

FIG. 4 is a diagram for explaining effects of the first embodiment ofthe invention;

FIG. 5 is a plan view showing a layout of the second embodiment of theinvention;

FIG. 6 is a plan view showing another form of the second embodiment ofthe invention;

FIG. 7 is a plan view showing a layout of the third embodiment of theinvention;

FIG. 8 is an explanatory diagram of an optical system of a cameraaccording to the fourth embodiment of the invention;

FIG. 9 is a schematic plan view showing a conventional layout;

FIG. 10 is a diagram for explaining a sensitivity within a cell of an AFsensor;

FIG. 11 is a diagram for explaining an output example of a conventionalAF sensor; and

FIG. 12 is a diagram for explaining a problem of the conventional AFsensor.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the invention will be described in detail hereinbelowwith reference to the drawings.

EMBODIMENT 1

FIG. 1 is a diagram most preferably showing a feature of the inventionand is a schematic plan view showing a layout of a solid-state imagepickup device to which the invention is applied. FIG. 4 is a diagram forexplaining a layout of linear sensor pairs and its effects.

In the diagram, reference numeral 1 denotes an Si semiconductorsubstrate; 2 photodiode arrays each constructing a linear sensor(photodiode arrays arranged vertically with respect to a centerdetecting point of the Si semiconductor substrate are shown at 2-1 to2-4); 3 an AF sensor readout circuit; 4 a scan circuit for scanning theAF sensor readout circuit 3; 5 a signal amplifying circuit foramplifying a signal from an AF sensor block; 6 a power source circuitfor making an analog circuit operative; 7 an AGC circuit for deciding anaccumulation time of the AF sensor and a gain of a signal outputcircuit; 8 a logic circuit (T/G) for driving the sensor; 9 a thermometerfor measuring a temperature of a chip; and 10 a multiplexer circuit(MPX) for selectively reading out various analog signals.

As shown in FIG. 1, at the center of the Si semiconductor substrate, thephotodiode arrays 2-1 to 2-4 vertically arranged with respect to thecenter detecting point are arranged in such a manner that the photodiodearrays 2-1 and 2-2 are arranged in parallel so as to be neighboring sothat their positions are relatively deviated (zigzag arrangement) andthe photodiode arrays 2-3 and 2-4 are also similarly arranged inparallel so as to be neighboring so that their positions are relativelydeviated (zigzag arrangement). The photodiode arrays 2-1 and 2-3construct the first linear sensor pair and the photodiode arrays 2-2 and2-4 construct the second linear sensor pair.

FIG. 4 shows an example of a layout of the photodiode arrays 2-1 and 2-2(it is now assumed that each photodiode array is constructed by fivepixels for simplicity of explanation). The photodiode array 2-1 isconstructed by photodiodes (photosensing units) 40-U1 to 40-U5. Thephotodiode array 2-2 is constructed by photodiodes (photosensing units)40-L1 to 40-L5. The photodiodes 40-U1 to 40-U5 and the photodiodes 40-L1to 40-L5 are arranged at the same pixel pitch. Although the pixelincludes a MOS transistor for resetting and a differential amplifierbesides the photodiodes as will be explained hereinafter, the MOStransistor for resetting and the differential amplifier are omitted andonly the photodiodes and the isolation regions are shown in FIG. 4. TheMOS transistor for resetting and the differential amplifier are providedin a light shielding layer 43 and formed so as to be adjacent to aphotodiode forming region, respectively.

Although the light shielding layer 43 is formed so as to shield theresetting MOS transistor and the differential amplifier from the light,no light shielding layers are formed between the photodiode arrays 2-1and 2-2 and between the photodiode arrays 2-3 and 2-4. The reason whythe light shielding layers are not formed is to reduce a non-sensitiveregion as small as possible, thereby allowing the photodiode arrays tobe neighboring. This is also because if the photodiode arrays are away,a positional deviation occurs and it is difficult to detect a finepattern. If the light shielding layer is narrow, there is notparticularly a problem even when the dead zone region exists.

FIG. 2 shows a specific circuit diagram of an AF linear sensor circuitcomprising the photodiode array 2 and the AF sensor readout circuit 3.FIG. 3 is a diagram showing specific circuit constructions ofdifferential amplifiers 29 and 30.

The AF linear sensor circuit (CMOS linear type AF sensor) shown here isthe circuit proposed before by the applicant of the present invention inJapanese Patent Application Laid-Open No. 2000-180706 or the like. TheAF linear sensor circuit is constructed by a plurality of AF sensorunits.

In FIG. 2, reference numeral 20 denotes a pn junction photodiode forexecuting photoelectric conversion; 21 a resetting MOS transistor forresetting an electric potential of the photodiode 20 to VRES; and 22 adifferential amplifier whose positive input terminal (+) is connected tothe photodiode 20 and whose inverting input terminal (−) is connected toits output terminal. An amplifying type photoelectric converting deviceis constructed by the pn junction photodiode 20, resetting MOStransistor 21, and differential amplifier 22 and becomes one of thepixels of the photodiode array 2.

Reference numeral 23 denotes a clamp capacitor and 24 indicates a MOSswitch for inputting a clamp electric potential into the clamp capacitor23. A clamp circuit is constructed by the clamp capacitor 23 and the MOSswitch 24. Reference numerals 25 to 28 denote MOS transistors forswitching; 29 the differential amplifier for detecting the maximumvalue; and 30 the differential amplifier for detecting the minimum valuealso serving as an AF signal outputting circuit. Each of thedifferential amplifiers constructs a voltage follower circuit. An outputof the differential amplifier 22 is inputted to the maximum valuedetection circuit through the clamp circuit and inputted to the minimumvalue detection circuit also serving as an AF signal outputting circuitthrough the clamp circuit.

Reference numeral 31 denotes a MOS switch for outputting the maximumvalue; 32 a MOS switch for outputting the minimum value; 33 an ORcircuit; 34 an NMOS transistor for a constant current; and 35 a PMOStransistor for a constant current. As shown in FIG. 3, the final stageof the minimum value detection circuit is a PMOS source follower circuitand the final stage of the maximum value detection circuit is an NMOSsource follower circuit. An output signal of the scan circuit 4 isinputted to the OR circuit, thereby allowing the minimum value outputsfrom the AF sensor units to be sequentially and selectively outputted.Reference numeral 36 denotes a common output line to which the signalsor the minimum value outputs from the pixels are outputted.

Since the details of the operation of the present circuit have alreadybeen described in Japanese Patent Application Laid-Open 2000-180706, theoperation will be schematically explained here.

The resetting MOS transistor 21 is turned on by a signal φRES, therebyresetting the photodiode. The switching MOS transistors 26 and 27 areturned on by signals φN1 and φN2, thereby allowing an output of thedifferential amplifier 22 to be held into the clamp capacitor 23 throughthe switching MOS transistor 25, the maximum value detection circuit(minimum value detection circuit), and the switching MOS transistor 27.The signal which is held in the clamp capacitor contains offsetcomponents of the differential amplifiers constructing the maximum valuedetection circuit and the minimum value detection circuit. The signalfrom the differential amplifier 22 is inputted to the clamp circuit.When the signal is outputted through the maximum value detection circuitand the minimum value detection circuit, the offset components of thedifferential amplifiers are also eliminated and the resultant signal canbe outputted. By turning all of the maximum value outputting MOSswitches 31 on by a signal φPEAK, the maximum value outputs can beoutputted to the AGC circuit. By turning all of the minimum valueoutputting MOS switches 32 on by a signal φBTM through the OR circuit33, the minimum value outputs are outputted to the common output line36. By sequentially turning on the minimum value outputting MOS switches32 by the scan circuit through the OR circuit 33, the AF signals areoutputted to the common output line 36 (at this time, the minimum valuedetection circuit is made operative as an AF output circuit). When theminimum value is outputted from the minimum value detection circuit 30,a constant current MOS transistor 38 in FIG. 3 is turned off. When theminimum value detection circuit 30 is operated as an AF output circuit,the constant current MOS transistor 38 in FIG. 3 is turned on.

In the construction of the present circuit, by providing the feedbacktype noise clamp circuits at the front stage of the maximum valuedetection circuit and the minimum value detection circuit, the resetnoises which are generated in the photodiodes and the FPN which aregenerated in the sensor amplifiers, the maximum value detection circuit,and the minimum value detection circuit can be eliminated. The voltagefollower circuit whose final output stage is a source follower circuitis constructed every pixel, the constant current source at the outputstage of each voltage follower is turned off at the time of the outputof the minimum value, and the voltage follower circuits are connected incommon to an output line connected to the constant current source, sothat the minimum value of the AF sensor signal can be obtained. At thetime of the output of the AF sensor signal, by turning on the constantcurrent source at the output stage of each voltage follower andsequentially connecting the voltage follower circuits to the outputline, the serial AF sensor signal can be obtained. Since the minimumvalue detection circuit is also used in common as a signal outputtingcircuit by the above operation, the chip can be miniaturized.

Effects of the linear sensors arranged in the zigzag manner will now bedescribed. FIG. 4 is a diagram using a part of the sensors arranged inthe zigzag manner and a slit-shaped object image for simplicity ofexplanation.

In FIG. 4, reference numeral 41 denotes an isolation region and 42 aslit light. In a sensor shown in FIG. 12, if the object image is formedon the isolation region, the operation becomes unstable. However, in thecase of constructing as shown in FIG. 4, the object image is formed onthe isolation region between the photodiodes 40-L3 and 40-L4 of thephotodiode array 2-2. Even if it is unknown that the peak of the objectimage exists in which one of the right and left diodes of the isolationregion, the object image is formed on the photodiode 40-U3 in the otherphotodiode array 2-1 and the peak position is unconditionallydetermined, so that the operation does not become unstable. Usually,since the signal process can be executed by using both of the linearsensor outputs, another effect in which the S/N ratio is multiplied by/2 also obtained. Therefore, the AF precision and detecting sensitivitywhich are higher than those of the conventional device can be obtainedeven in the case of the same pixel size as that of the conventionaldevice without an unreasonable decrease in pixel pitch.

In the embodiment, the linear sensors having different base-line lengths(each of which is a distance between the optical center of the linearsensor for the base portion and that of the linear sensor for thereference portion) are further provided at positions whichperpendicularly cross the linear sensor pairs arranged in the zigzagmanner. As shown in FIG. 1, a linear sensor pair (2-5, 2-8) of abase-line length B is provided outside of a linear sensor pair (2-6,2-7) of a base-line length A (B>A). It is desirable that the linearsensor pair (2-6, 2-7) of the base-line length A and the linear sensorpair (2-5, 2-8) of the base-line length B are arranged on the samestraight line to prevent a deviation of a field of view. Since thesensitivity (AF resolution) of the linear sensor pair of the largerbase-line length is higher, the AF of the higher precision can berealized. However, since a light beam obtained through the photographingLens whose F number is small is used, there is such a restriction thatthe above construction cannot be used for a dark lens (F number islarge). However, since a depth of field of the photographing lens whoseF number is large is large, no problem will occur.

In the embodiment, the first linear sensor pair (2-1, 2-3) and thesecond linear sensor pair (2-2, 2-4) are arranged at theline-symmetrical positions (flip layout) while deviating the secondlinear sensor pair (2-2, 2-4) in the arranging direction of the linearsensors (photodiode arrays) by the length corresponding to the halfpixel (0.5 pixel). The arranging direction of the linear sensors(photodiode arrays) is, for example, the arranging direction of thephotodiode array (linear sensor) 2-1 and the photodiode array (linearsensor) 2-3. If there is no aberration in the 2-dimensional imageforming optical system, it is optimum to deviate the linear sensors(photodiode arrays) by 0.5 pixel as shown in the embodiment. However, ifthere is an optical aberration, it is desirable to deviate them by adistance within a range from 0.5 to 1 pixel in order to allow correctionof the optical aberration to be included. However, a deviation amount ofthe linear sensors is not particularly limited but the effects of theinvention can be obtained so long as there is an arbitrary deviation.

Although there is such a problem that, in general, when the number oflinear sensor pairs increases, the speed decreases, in the embodiment,by independently drive-processing the accumulation time control (AGC) ofthe linear sensor pairs in parallel, both of the high speed and the highprecision are realized. The method whereby the AGC is independentlycontrolled has been disclosed in, for example, Japanese PatentApplication Laid-Open No. 2003-107340.

Therefore, even if the number of linear sensors increases, the speed isnot decreased and the high response speed that is equal to that of theconventional device can be realized. It is desirable to make theaccumulation time control in a real-time manner. Also with respect tocurrent consumption, since the CMOS circuits are used, no problem willoccur. In the embodiment, not only the photoelectric converting devicesbut also all of the (logic, analog) devices are constructed by the CMOScircuits and the CMOS type solid-state image pickup device which can bemanufactured by the CMOS processes is constructed (it is not alwaysnecessary to form all of the component parts by the CMOS circuits).

It is preferable that all of the photodiode arrays 2 (including thephotodiode arrays 2-1 to 2-8) constructing the linear sensors are set tothe same pixel size (layout pitch). By setting them to the same pixelsize, the developing load, the developing period of time, and thedeveloping costs can be reduced. Since the photoelectric convertingcharacteristics are also equalized, a correction system (sensitivityvariation, shading, and the like) is also simplified.

In the embodiment, the solid-state image pickup device for the AF havingthe AF ability of the high precision, high stability, and highsensitivity can be realized although the same manufacturing processesand design rules as those of the conventional device are used.Naturally, the embodiment can be also applied to a VMIS (ThresholdVoltage Modulation Image Sensor), a BCAST (Buried Charge Accumulator andSensing Transistor Array), an LBCAST (Lateral Buried Charge Accumulatorand Sensing Transistor Array), and the like. Particularly, with respectto the BCAST and LBCAST, such a device can be realized without anessential change by replacing the amplifying MOS transistors by JFETtransistors.

EMBODIMENT 2

FIG. 5 shows a plan view of a layout in the second embodiment to whichthe invention is applied. In FIG. 5, the same component elements asthose in FIG. 1 are designated by the same reference numerals and theirdetailed description is omitted here. In the second embodiment, thelinear sensors arranged in a zigzag manner are also provided in the AFline of a large base-line length. That is, photodiode arrays 2-11 and2-13 construct the first linear sensor pair and photodiode arrays 2-12and 2-14 construct the second linear sensor pair. Photodiode arrays 2-9and 2-15 construct the first linear sensor pair and photodiode arrays2-10 and 2-16 construct the second linear sensor pair. According to theembodiment, at the center detecting point, the focusing precision andsensitivity can be further improved. The linear sensors which arearranged in a zigzag manner can be also provided at all detecting pointsas shown in FIG. 6. In FIG. 6, the same component elements as those inFIG. 1 are designated by the same reference numerals. Further,naturally, the invention is also effective even in the case where thenumber of detecting points is increased like 11-point AF, 15-point AF,or the like.

EMBODIMENT 3

FIG. 7 shows a plan view of a layout in the third embodiment to whichthe invention is applied. In the third embodiment, an example in whichthe invention is applied to an area type AF sensor is shown. The areatype AF sensor has been disclosed in Japanese Patent ApplicationLaid-Open H11-191867 or the like by the same applicant as the presentinvention. In the diagram, reference numeral 50 denotes a photodiode; 51an isolation region; 52 a pixel amplifier region for amplifyingphotocharges; 61 to 64 effective pixel regions; 65 an SRAM; 66 amultiplexer circuit (MPX); 67 a logic circuit & I/O circuit; 68 to 70AGC circuits; 71 a signal amplifying circuit; and 72 a power sourcecircuit. Although the TTL passive-type phase detection system AF isexecuted by the linear sensor pairs in the embodiments 1 and 2, the TTLpassive-type phase detection system AF is executed by the area sensorpairs in the embodiment 3. It is a feature of the embodiment 3 toexecute the AF by the two area sensor pairs arranged in a zigzag mannerso as to be neighboring as shown in FIG. 7. By using the area sensor,the auto-focus for a wider region can be executed. Also in theembodiment, the high precision and the high sensitivity of the AFability of the area type AF sensor can be realized.

EMBODIMENT 4

FIG. 8 shows a schematic diagram of an optical system of a single-lensreflex camera in which the TTL-SIR type auto-focus system using theinvention has been installed. In FIG. 8, reference numeral 80 denotes aphotographing lens for temporarily forming an object image onto a filmor an image sensor and 81 indicates a quick return mirror for reflectingthe light to a finder screen 82; The quick return mirror 81 is a halfmirror which transmits the light of tens of %. Reference numeral 83denotes a submirror for guiding the light to the AF system; 84 asolid-state image pickup device for the AF; 85 a secondary image forminglens (glasses lens) for forming the object image again onto the AFsensor; 86 a reflecting mirror for guiding the light to an AF sensor 44;87 a focal plane shutter; and 88 a principal axis of the light beam.

In the embodiment 4, by using the solid-state image pickup devices forthe AF disclosed in the embodiments 1 to 3, the single-lens reflexcamera having the higher focusing precision than that in theconventional device can be realized without raising the costs.Naturally, the invention is not limited to an analog camera and adigital camera, it can be also applied to an arbitrary TTL-SIR typecamera.

The invention can be applied to an apparatus with an auto-focus sensorof the TTL-SIR (Through The Lens Secondary Imaged Registration:secondary image forming, phase difference detection) type, for example,an auto-focus camera or the like.

This application claims priority from Japanese Patent Application No.2004-115629 filed Apr. 9, 2004, which is hereby incorporated byreference herein.

1. A solid-state image pickup device for an auto-focus comprising firstand second linear sensor pairs each having a linear sensor for a baseportion with a plurality of pixels and a linear sensor for a referenceportion with a plurality of pixels in order to perform a focal pointdetection of a phase difference detecting type, wherein said firstlinear sensor pair and said second linear sensor pair have a same pixelpitch, said first linear sensor pair and said second linear sensor pairare neighboring in parallel and are arranged so as to be relativelydeviated in the arranging direction of said linear sensor for the baseportion and said linear sensor for the reference portion, and a signaloutput to detect the focal point is executed by using both of said firstlinear sensor pair and said second linear sensor pair, a third linearsensor pair arranged in a direction which perpendicularly crosses saidfirst and second linear sensor pairs; and a fourth linear sensor pairhaving a base-line length larger than that of said third linear sensorpair, and wherein said fourth linear sensor pair is arranged outside ofsaid third linear sensor pair with respect to a direction of saidbase-line length, and wherein said third linear sensor pair and saidfourth linear sensor pair are arranged on a same straight line.
 2. Adevice according to claim 1, wherein a deviation amount between saidfirst linear sensor pair and said second linear sensor pair is equal toalmost 0.5 pixel.
 3. A device according to claim 1, wherein aphotosensing unit of the pixel of said first linear sensor pair and aphotosensing unit of the pixel of said second linear sensor pair arearranged so as to be neighboring.
 4. A device according to claim 3,wherein there is no light shielding layer between photoelectricconverting devices of said first linear sensor pair and said secondlinear sensor pair.
 5. (canceled)
 6. (canceled)
 7. A solid-state imagepickup device for an auto-focus for executing a multi-point detectionwith respect to a plurality of object positions, wherein a sensor forauto-focusing the object of at least the center of a display screenincludes said first and second linear sensor pairs according to claim 1.8. A solid-state image pickup device for an auto-focus for executing amulti-point detection with respect to a plurality of object positions,wherein a sensor for auto-focusing the object of at least the center ofa display screen includes said first to fourth linear sensor pairsaccording to claim
 1. 9. A device according to claim 1, wherein allof-said linear sensor pairs have a same pixel shape.
 10. A deviceaccording to claim 1, wherein said first to fourth linear sensor pairsindependently control an accumulation time of photocharges of aphotoelectric converting device constructing said pixel.
 11. A deviceaccording to claim 10, wherein said photoelectric converting device isan amplifying type photoelectric converting device and the control ofsaid accumulation time is made by using said amplifying typephotoelectric converting device in a real-time manner.
 12. A deviceaccording to claim 11, wherein said solid-state image pickup device is aCMOS type solid-state image pickup device which can be manufactured by aCMOS process.
 13. An auto-focus camera having the solid-state imagepickup device for the auto-focus according to claim 1.